Paper-based labels for bottles, cans and other containers are commonly employed. As used throughout this specification, the term paper-based label refers to a label, either coated and/or laminated, including a paper layer. Examples of such paper-based labels include metallic foil-paper laminated labels, such as aluminum foil-paper laminated labels, metallized paper labels, such as aluminized paper labels, coated paper labels, such as varnished paper labels, and plastics resin film-paper laminated labels. When using these paper-based labels, the labels are stacked into a labeling machine which transfers the labels from the stack to the containers to be labeled.
As speeds of the labeling machines have increased, i.e., increased numbers of labels and containers being handled per unit time, it has become increasingly important that the labels remain as flat as possible as they are stacked into the labeling machines. Paper-based labels do not lie flat well, of themselves, especially under conditions of excessive humidity.
Another highly desirably property for a label is water holdout. Water holdout is the ability of a material to resist water penetration. Paper generally has extremely poor water holdout properties and must thus be treated to provide these properties. When treated, these labels will provide improved gluability to the bottles, cans and other containers on which they will be placed.
Still another property desired for labels, which must feed efficiently through a magazine on the labeling equipment and be molded around the bottles, cans, and other containers, is flexibility. If the labels do not have a high degree of flexibility, tearing or jamming of the labels in the labeling machine can occur when the labeling machine attempts to place the labels on the containers.
U.S. Pat. No. 3,098,780 discloses only a method of application of treatings to the paper layer of a laminated metallic foil-paper label for increasing the curl resistance of the label by preventing the paper layer from picking up moisture. No mention is made, however, of either providing a label with a higher degree of flexibility or a higher degree of water holdout. Further, this patent requires that the paper layer be flooded with the treating solution and dried to a specific moisture content. Such flooding wastes valuable treating compound and controlled application of the compound is difficult. Thus, it is desirable to avoid this procedure.